The present invention relates to testing apparatuses used to test components of a motor vehicle. More particularly, the present invention relates to a testing apparatus used to test tire, wheel, spindle and/or braking components of a motor vehicle.
A rolling wheel testing apparatus using the inside of a rotating drum was developed by the Fraunhofer-Institut Fur Betriebsfestigkeit and has been shown to be an effective test technique. Generally, a tire and wheel are mounted to a drive motor and is disposed within a drum where the tire engages an inside circumferential surface. Improvements have been made on the original design to simulate loading when the tire and wheel rim are mounted to a motor vehicle as the motor vehicle travels down a road. The loading can include radial wheel loading to simulate the weight and dynamic loading of the vehicle and lateral loading where the load is applied along the axis of rotation of the tire and wheel rim. In yet further embodiments, applications of driving and braking torque have also been proposed in “Adapting the Biaxial Wheel Test System for Brake Components and Lug-Loosening”, published in the Proceedings of the 3rd International User Meeting, Sept. 11, 1997, Darmstadt, Germany.
Although the original design has been found effective and improvements have been made to simulate road conditions, shortcomings are still present. For instance, the radial and axial forces acting on the vehicle wheels are not constant, but are dependent on a variety of factors. In order to duplicate forces acting on vehicle components, strain gauges are commonly provided on components of interest and the vehicle is driven under real world conditions and data is collected therefrom. Actuators are operated to apply loads to vehicle components in the laboratory having similar strain gauges to approximate the loads seen during real world conditions. However, a complicated setup procedure (i.e. mapping process) is required before testing can even begin. For instance, a test wheel rim or wheel rims incorporating strain gauges can be used in the laboratory for setup. Forces are then applied, and the strain gauge outputs are monitored to determine if the desired strain fields exist in the test wheel rim. The machine camber angle settings of the wheel assembly along with applied forces (load pair) are iteratively adjusted, until the strain field readings are satisfactory. This setup procedure complicates testing because it takes a considerable amount of time as well as causes wear upon the test specimen.